Apparatus and method for preventing



Feb. 7, 1956 R. l.. LE BARRoN 2,733,649

APPARATUS AND METHOD FOR 'PREVENTING ICE FORMATION UPON BUILDING ROOF'S Flled Aprll 25, 1952 W AWM/irs United States Patent O APPARATUS AND METHOD FOR PREVENTINGv ICE FORMATION UPON BUILDING ROOFS Ralph L. Le Barron, Minneapia, Mimi.

Application April 25, 1952, Serial No. 284,409

4 claims. (cl. 9s1) This invention relates to the prevention of the formation of ice upon the outside `surface of a building roof and more particularly to apparatus and a method for maintaining the outside surface of a building roof at n temperature such as to prevent the build-up of ice at the lowermost portions of the roof.

The problem of ice formation upon the roofs of dwellings and industrial buildings has long been a serious problem. The recognized methods of coping with thejice have included such drastic and costly procedures as physically chopping away the ice formation as soon as it becomes bothersome and, on the other hand, installing elaborate heating elements throughout the gutters, downspouts and valleys of roofs so as to melt the ice after it has formed thereon. To my knowledge, none of the prior methods have approached the problem from the standpoint of preventing initial melting of ice and snow over the entire outside roof area before such build-up of refrozen melted ice can accumulate. The problem of ice formation is extremely serious and costs the owners and proprietors of buildings many thousands of dollars throughout the so-called snow belt during each winter season. ofv ice at the portions of the roof not subject to the effect of internal heat within the building. Thus, the accumulation of dry snow which falls upon a roof of a building may melt in certain portions, especially toward the hip or peak of the roof over which internal heat rises and the resulting water trickles downwardly to the overhanging eaves, gutters, or valleys where the outside air belowV the freezing temperature will again cause the water to freeze into vicicles. and accumulations of ice. Once having formed,-when the process is repeated the next downward trickling of water brings up the ice layers still fur` ther and finally causes the accumulatingk water to dam up behind the ice. When this occurs the water will find its way backwardly through the roofing of the building and ultimately seep into the walls and through the ceiling of the Ibuilding. kThe Vdestruction of decorative workand the rotting of woodwork as well as destiuction of insulation material has been all too thoroughly impressed' upon the minds of building owners and proprietors who have sufferedtherefrom.

lt is therefore another object of this inventiontoprovide for a simple and positive method of preventing the formation of harmful ice upon the roofs of buildings by maintaining a low temperature differential across the roof surface during that period of time when the outside temperature is at the freezing point of water or lower.

It is a further object of the invention to provide for an `efficient and'economical method of preventing the formation of ice bythe replacement of warm attic airV by cold outside atmospheric air only during such time as the temperature differentialV would tend to cause the formation of ice. l t n It isastill-fur'th'er object of the invention to provide for novel ndpsimple apparatus for coolingthe inside Theproblem arises largely from the build-upv perature is below the melting point of ice.

2,733,649 Patented Feb. 7, 1956 ICC atmosphere beneath the roof of a dwelling in response made in connection with the accompanying drawingsv wherein like reference characters refer to similar parts throughout the several views and in which:

Fig. l is a perspective view of a home having a hip roof through which are installed a plurality of Ventilating louvers in accordance with my invention; l

Fig. 2 is a vertical section taken through the roof portion of the dwelling shown in Fig. l on the lines 2-2 of Fig. 1; and

Fig. 3 is a diagrammatic representation of the electrical circuit for operating my fluid propeller, including the dual thermostatic control;

Referring now more particularly to the drawing, the letter H refers to an ordinary small dwelling having a hip roof R beneath which is an attic space S and an insulated attic floor 10 which should be insulated by some efficient material 11 such as mineral ber. Spaced at strategic points upon the surface of the roof R are lower louvers 12 and an upper louver 13. These louvers l2 and 13 may be of ordinary form, being constructed of sheet metal and having a downwardly facing opening 14 communicating with the space S within the attic. A fluid propeller unit 15 is disposed beneath the upper louver 13 in the passageway 16 communicating between the space S and the outside atmosphere. An electric moto-r M is mounted in driving connection with the uid propeller 15 so as to force the inside air within the space S without the building and to replace it by outside atmospheric air. The electric motor M is energized by a conductor comprising leads 17 which may be connected to a suitable source of current. Disposed in the circuit estab lished by conductors 17 are first an outside thermostat 18 preferably mounted beneath the eave 19 of roof R so as to be shielded from the weather but still subject to the variations in outside temperature. A second thermostat 20 is placed in series with the rst thermostat 18 in the motor circuit and is preferably positioned at a point immediately under the roof R Within the space S and adjacent the peak of the roof. The outside thermostat 18 is abelow-freezing thermostat which will operate to close electrical contacts 21-22 when the outside tem The thermostat 20'on the other hand is an above-freezing thermostat interposed in said circuit in series with thermostat, 18, which operatively responds to an inside temperature within space S which is abovethe freezing point of water.v

When thus operating the contact points 23-24 are closed to establish the circuit.' AIt will be noted that it is not depending upon the transfer factor or insulation value of the roof structure. I prefer to maintain the thermostat 18, on the other hand, at a very close cut-intsetting, the thermostat serving to close contactsZl-ZZ exactly at the point of temperature drop at which water freezes, namely at 32 F.

t In the operation of my device l install inlet louvers`12 at 4strategic points about the lower edgesfof the roof ac c'ordingto the complexity oft-hey roof structurel Thus,

whsre. there are.. numerous, gutters.. and vallei/.5.1. prefer.` to have adequate ventilation at these particular points. Since the movement of air under such circumstances is commonly known and understood:A to heating. and ventilat-f ingA engineers, it willI be;` apparenti to those'skilledin the art .how to. space the lowcrxlonrers, 12..;in order. to: insure the most complete movementand replacement` attic air; under my forced ventilation system. Although'l show but one, upper louyer 13, itis: understoodithat.herelagairn in caseof largebuilding structures having'elongated or broken` roof structures, l may employ a; plurality of.. such upper louversfif eachis suppliedi witha lluidpropellenls forY exhausting theair uniformly from' within. the entire space S. It will he, understood` that eachr` of, the motor` and propeller unitsmay be attached'tofthehousing defining the passageway 1,6 so asyto exhaust air through its louver 1,3.

When the outside atmospheric temperature is. at: or below freezing, the contacts 2,1 andZZ ofthermostat 18 will become closed and establish an electrical. circuit there*-` through. If, at the same time, the inside air within-space S is of such a temperature as to ca use h eat transfer through the roof structure suliicient to bring the; outside surface` thereof to the melting point of ice, thenthe thermostat 20 will respond thereto and contacts 33-34 will be closed4 and the motor M and propeller 15 willbe energized. During the running period of: motor M outside atmospheric air will be drawn into lower louvers 12 while the warm inside. air will be discharged through the upper louver13. When the ternperatureof4 the air-within spacer S has been lowered below thatrwhichvwill causethe outer surface of the roof to melt ice, the thermostat 20 willi, respond by separating the contacts 23-.2 4 and consequently stopping the operation of motor M. T hethermo` stat 1,8 will remain closed; as long as the outside; teme perature is at or below freezing, Ifv the outside temperature warms to thawing point and snow upon the: roof R begins to melt fromexternal,V temperatures, then, the motor M is not needed and will not beenergizedY even though the contactpoints, 23-24 ofV thermostat` 20 re.A main closed.

When the outside temperature is extremely cold the; temperaturek within the space may be. at amuch higher. point than the normal cut-in temperature of thermostat; 20 and still without furnishingsuicientheat tomelt snow.` lying upon thesurface of roof R. The locationrof ther-. mostat 2,0` compensates to some degree for thistempcrafture differential since it respondsto an interrped,iatey tem-r perature somewherebetweenthe temperature. of the` innerl surface of roof R andthe temperatureof inside'fair within, the attic space S. This variation in response-is useful` in; that the motor, M willnot berequired to run oftener than: necessary to chill the air in attic space.- Sto apointcomf mensurate with the outsidey temperature,l B y wayfof e2 r. ample. where, the outside. temperature at 30' it may bs, necessary to chilltheatticfspaceifto .73.4 to nractice my inyntone. O11.. the other hand when; the Outsidetemi perature is,` for example, at 10; below; zero F. itlmay be necessary to chill the atticspace S merely to 554- or 6,O 9 E.

It will be observedl that no harm is` accomplishedby'A the natural outside thawing of` snow upon the building` roof. Since the ambient` temperature. is above freezing, any trickling of4 water from the, roof,` will` continuato` be,

discharged through. the gutters. valleys and dnwusnouts- Wifdmut' freezing. and' dammig, tlicruf-` Since. we arec oncerned with. reducing `the fairf' temperature., of the; space- S` merely to a point approaching the freezing; point, of; water the heatloss from the inside of therooms below` the attic tloor 10is no appreciable and thisis especially true itr the attic, floor is properly. insulated as, at 11,. Oneoffthcbiggest" sources of trouble is hea; from, the` rays f the Sun. impinsing P011 the Surface., Qfjroof.; R whilthetoutside, atmospheric temperature remains'. below freezing Under: such circumstances-the space S will baheutecttoa highertempcraturethaneis-even compatible i ranging an air inlet passageway and' an air outlet passageway said passageways communicating between the outside atmosphere and said space, mounting a motor driven tluid propeller upon said building in one of said passageways, applying energy to said motor through a rst thermostat operatively responsive to interrupty said energy when subjected to outside atmospheric temperatures ranging from in the neighborhood of thefreezing point of water and upwardly and through aI` second' thermostat operatively responsive to interruptl said energywhen subjected to inside space temperatures ranging from in the neighborhood of the freezingv point of'water and downwardly.

2. Apparatus for preventing-the formation of ice-upon the outside surface of the roof of av building having aspace between the roof and the ceiling-.thereof which comprises in combination a fluid propellerfor mounting across' av passageway from said space to the outside atmosphere, an electric motor in drivingy connection therewith, a second passageway from said space to tliey outside atmosphere remotely positionedv from said firstV mentioned passageway, an electrical conductor connectedto'. said., motor for energization thereof through an electrical circuit, means interposed acrosse said'- conductory operatively responsive to outside atmospheric temperatures, below the melting point of' ice to maintain said electrical circuit energized, and' means interposed' acrosssaid? conductor in series with said first-mentioned means and operatively responsive to inside.4 space temperatures above; the freezing point of water, whereby said electrical f i circuit will be maintained to energize said motor and= uid propeller to continuously replace the air in' saidi space, with outside atmospheric'air as'v longi as` saidi out;v sideI airA scapable offreezing wateron said roof surfacen and said, inside` space air is capable of warming'the roof surfacesto the melting'point of water.

3. Apparatus for preventing the4 formationofice upon; theoutsidesurfaceofthe roofof abuilding having al space between, the roof and the ceiling thereof` whichl comprisesin combination a uidpropellen formounting across,` a passageway from saidV space to thev outsideatmosphere; electric motor in driving connection therewith, a second .passageway from said' spaceto the outside atmen.4 Eher@ remotely positioned from said` rstm'entioned RaSWay, an electrical conductor connected? to; saidl motor` for energizationz thereof throughA anl electrical circuit,` aV below-freezing thermostat interposed: across, said conductor operatively responsive to outside atmospheric temperatures below the meltingpoint' of ice to maintainy said, electrical circuit,-v energized, and an aboveffreezing thermostatk interposed. across sad= conductorin seriesV with, saidV below-freezingV thermostatoperatiyely responsive-'to inside space-temperatures above the freezingpoint of water, whereby saidelectrical circuit will bemaintainedl to energize said motor and uid propeller to continuously. replacer the air` in said spacer with outside-atmospheric; air:A as longl as said"v outsid`e-airy is capable o f freezingv water on, saidt rooff' surfaceandr4 said, inside. space air; is; capable.. off warming@ the roof( surface to the melting point of Water.

4.-. A. method, for corltrolliriglr moisture; and.` inertia. and around the roof.. Structure of... a; house harina an: attic space, which consists in electrically energizing a motordriven blower and thereby forcibly sweeping attic air out and external air in, thermostatically interrupting electrical energy in the blowing operation in response to an outside atmospheric temperature when in the neighborhood of the freezing point of water and upwardly, and 5 independently thermostatically interrupting the same electrical energy in the blowing operation in response to an inside air temperature when in the neighborhood' of the freezing point of water and downwardly.

References Cited inthe ile of this patent UNITED STATES PATENTS 

